It has long been recognized that buildings stay warmer in cool climates and cooler in warm climates when certain materials having thermal insulating properties are used in the walls, ceiling and floor of the building. It is common practice to build the frame of a building, attach one wall, and then fasten an insulative material to the first wall and frame before attaching the second wall thereby sandwiching the insulative material. When various energy sources became more and more scarce, it became more and more common to increase the distance between the walls and also increase the amount of insulative material therebetween. As construction costs increased, it became more common for builders to rely on prefabricated components.
A number of patents show various types of building constructions which use various prefabricated, insulated panels. U.S. Pat. No. 3,203,145 is illustrative of a prefabricated, modular home construction. Panels having interior and exterior skins with a central core of insulation material are shown. In addition, there is disclosure of formed metallic mechanism for attaching the panels to a cement slab floor and formed metallic mechanism for attaching the wall panels to roof panels. The roof panels are shown to come together at a central metal beam in order to provide a vaulted ceiling.
U.S. Pat. No. 3,641,720 shows a prefabricated building with interfitting stud splines. Prefabricated panels with outer skins and an insulating filler have edges in the form of metal sockets to receive box-type, metal stud splines. In some cases, the wall panels wrap sufficiently about the stud splines so that some insulation is located on all sides of the stud spline. As well as providing structural strength, the stud splines also form conduits for electrical wiring. Additionally, a formed metallic mechanism for attaching roof panels is shown.
U.S. Pat. No. 4,163,349 also discloses insulated building panels with interior and exterior skins and an insulated core. A corner construction more applicable to the usual frame house is shown. A square wood stud is received between the exterior and interior skins at a vertical edge of a corner panel. A second rectangular stud is attached adjacent the corner to the interior skin. The mating corner panel from a second wall receives the second stud between its interior and exterior skins such that the interior skin butts against the interior skin of the first panel and the exterior skin reaches across to cover both studs and butt against the exterior skin of the first panel.
Despite these and other various attempts of builders, construction engineers, and inventors to enhance the thermal properties of a building construction, there continues to be substantial cost and performance considerations. Most constructions have, for example, a number of areas which qualify as "thermal shorts". That is, most of a wall or panel is well insulated; however, an adjacent element includes a path having good thermal conduction characteristics or includes a crack allowing a convection current to pass through which in either case provides for the passage of heat. For example, both U.S. Pat. No. 3,641,720 and U.S. Pat. No. 3,203,145 utilize various metal structural components which include cavities. Metal has very good thermal conduction characteristics and, consequently, is a "thermal short". The various cavities provide excellent channels for convection currents. Furthermore, the ordinarily large number of metal components around the walls and ceiling of a building creates a large number of "thermal shorts"and, consequently, much of the cost which has gone into expensive insulated panels may well be wasted. Additionally, the various metal studs and other stuctural members are themselves very expensive. Even U.S. Pat. No. 4,163,349 which utilizes wood studs provides for greater thermal conduction across the wood stud than is otherwise the case through the insulated panel. Thus, a certain pressure continues within the industry to provide building construction having better thermal characteristics while maintaining or reducing cost.